Rate Constants for the Gas‐Phase Reactions of Ozone and Nitrate Radicals with the Sesquiterpenes: Valencene and Farnesol

Sesquiterpenes are constituents of a variety of essential oils that are used in flavorings, perfumes, personal care, and cleaning products. Two sesquiterpenes that are commonly used as indoor fragrances are valencene and farnesol. Knowing the reaction rate constants of these chemicals with ozone (O₃) and nitrate radical () is an important factor in determining their fate indoors. In this study, the bimolecular rate constants of , , , and were measured using the relative rate technique at 297 ± 3 K and 1 atm total pressure. Using the rate constants reported here and measured/modeled indoor concentrations of O₃ and (20 ppb and 1 ppt, respectively), pseudo–first‐order‐rate lifetimes , , , and were determined.     

Characterization of Polyethylenimine

Polymerization of anhydrous ethylenimine proceeds to completion with destruction of the terminal 1-aziridinyl group at relatively low molecular weight. In the absence of evidence for end groups, it is suggested that the chain terminating process is the formation of large rings composed of repeating CzHs N units.

Information is given on the various intermediates present in the early stages of polymerization of ethylenimine and on analytical techniques for determining the degree of branching in polyethylenimine.     

Antepenultimate Copolymer Composition Equation

A new reduced copolymer composition equation weighing the effects of units through the antepenultimate is derived for the first time. The simplification obtained is placed into context with previously published work.     

Role of Triad Concentration in Glass Transition Temperatures of Copolymers

Equations are presented weighing the contribution of triad sequences to copolymer T_g s. Improved correlation is shown for acrylonitrile-methyl methacrylate copolymer and suggested for certain other systems.

Certain simplified correlations between T_g of random copolymers and T_aa, T_bb, and T_ab are presented.     

Editorial

Abstract

Asymmetric syntheses of optically active polymethacrylate, polyacrylate, polyacrylamide, and polyisocyanate with helical conformation and their chiral recognition abilities are described. 1-Phenyldibenzosuberyl methacrylate (PDBSMA) gave a purely onehanded-helical, optically active polymer ([α]₃₆₅ +1670 ～ +1780º) with almost perfectly isotactic structure by anionic polymerization using optically active initiators. Radical polymerizations of PDBSMA using chiral initiators, chain transfer agents, and additives also afforded optically active polymers with a prevailing onehanded helicity. Triphenylmethyl acrylate yielded an optically active, helical polymer ([α]₃₆₅ +102º) having a dyad isotacticity of 70% using an optically active anionic initiator. Although the polyacrylate demonstrated chiral recognition ability as a chiral stationary phase for HPLC, the ability was low mainly because of the low degree of one-handedness. N-(3-Chlorophenyl)-N-phenylacrylamide gave an optically active, helical polymer ([α]_365–343º) in the asymmetric anionic polymerization; the polymer had a dyad tacticity of 77%. Optically active polyisocyanates with a predominantly one-handed helical conformation were prepared in homo-and co-polymerization of optically active phenyl isocyanate derivative. These polyisocyanates showed the ability to discriminate enantiomers in solution.